Endocytosis Mechanism And Risk Factors Of Alzheimer’s Disease

PART ONE: CLATHRIN, PICALM IN THE EARLYSTAGE OF ALZHEIMER’S DISEASE CELL MODELBackground/Aims: Recent studies show that Alzheimer’s disease(AD) and clathrin-mediated endocytosis (CME) are closely related. Thelevels of some key proteins of CME are abnormal in AD. Earlypathological changes in the AD such as amyloid β protein (Aβ) or N-methyl-D-aspartate (NMDA) receptor may be related to CMEdysfunction. Hence the aim of this section is to investigate the relationshipbetween CME and AD.Methods: Firstly optimize culture techniques and obtain high purityof cortex neurons. Then establish AD cell model by Aβ1-42oligomer. Finaly,detect clathrin and Phosphatidylinositol binding clathrin assembly protein(PICALM), the key protein of CME, in AD cell model by ReverseTranscription-Polymerase Chain Reaction (RT-PCR) and western blotting(WB) from transcription to translation.Results: Compared with the control group, in1μM group (1μMAβ1-42oligomers for1h) the morphology of cortex neuron had no obviouschanges and the metabolic rate decreased significantly (p<0.05); in5μMgroup (5μM Aβ1-42oligomers for1h) apoptosis was obvious and themetabolic rate significantly decreased (p<0.01). Hence select1μM for ADcell model. The results of RT-PCR, WB and cell immunofluorescenceshowed that in the AD model the expression level of clathrin protein and mRNA decreased significantly (p<0.05), the PICALM protein and mRNAexpression had no significant change(p>0.05).Conclusion: Clathrin, PICALM are key protein of CME. In thenervous system clathrin bind to cell membrane by PICALM and formclathrin-coated vesicles（CCV)，the primary structure of CME. Thereforeclathrin increasing without high PICALM level by Aβ perhapse leads toCCV structure abnormalities. The inconsistent level between clathrin andPICALM may be the main reason for the CME dysfunction in AD. PART TWO: TIME-DEPENDENT INCREASE OFCHITINASE1IN APP/PS1MICEBackground/Aims: The literature report chitinase1increass incerebrospinal fluid and peripheral blood of AD. While combined chitinase1,Aβ and Tau the AD diagnostic accuracy is up to91%. Hence it is suggestthat Chitinase1is the next reliability diagnosis index for AD. However, wehave few knowledge of chitinase1in AD from current studies. So wedesign to detect chitinase1level in different clinical stages of APP/PS1double transgenic mice.Methods: Morris water maze test detects cognitive function of4months and12months old APP/PS1double transgenic mice and agematched wild-type (WT) mice. ELISA method and the quantitativereal-time reverse transcriptase-polymerase chain reaction (qRT-PCR)detect chitinase1level in different groups.Results: In the hidden platform period the escape latency of the two4months old groups did not show significantly difference (P>0.05), and theescape latency of the12months old APP/PS1group significantly increasedcompared with the12months old WT group (P <0.05). The result ofELISA method and qRT-PCR showed chitinase1protein and mRNA levelincreased significantly in12months old APP/PS1group compared with12months old WT group ande4months old groups, respectively (P <0.05),while there was no significant different among latter three groups (P>0.05).Conclusion:4months old APP/PS1mice has spatial learningdisability and normal spatial memory impairment; both of them in12months old APP/PS1mice were decreased. It is suggested that4months old APP/PS1mice is for the early stage of AD and12months old is formiddle-late stage. Chitinase1level had no difference in different WTgroups and increased in the12months old APP/PS1group. Hencechitinase1is not related to age and it may be a sign of cognitiveimpairment. PART THREE: THE CORRELATION BETWEENCOGNITIVE IMPAIRMENT AND MALNUTRITIONBackground/Aims: Cognitive impairment is common symptoms inthe elderly which has bad influence on the life quality and the economic.Meanwhile it can not be cure at the current medical technology. Thepathogenesis is the only thing that we seemingly have the ability to hold,but most of the time it is a vain. Hence master the risk of cognitiveimpairment to be more important for its prevention and treatment.Methods: In April2011to October2012, All participants (±60years)were recruited to finish comprehensive geriatric assessment (CGA) fromDepartment of Geriatrics, the First Affiliated Hospital of ChongqingMedical University and Nanqiaosi community health center. CGA includesthe questionnaire, physical and laboratory examination. Questionnaire isdivided into demographic data, chronic diseases, nutritional status (MiniNutritional Assessment Short Form) and depression (Geriatric Scale),cognition (Mini Mental State Examination, MMSE), daily life (Activitiesof daily living), life style and social support. CGA was performed by twogeriatricians trained professionally face to face at the study site.Results: The mean age was73.1±8.0years and43.9%were men. Themean score of MNA-SF and MMSE was12.5(SD=1.9,4-14),27.1(SD=2.1,10-30), respectively. Prevalence of malnutrition and risk for malnutritionwas3.2%and19.3%, respectively. The prevalence of cognitiveimpairment was18.8%. Mild cognitive impairment was associated withnutrition status. Fish decreased the risk of poor nutrition.Conclusion: Compared with the good nutrition, cognitive impairmentis prevalent in the elderly with poor nutrition. Hence keep good nutrition status may delay progression to dementia. Fish may be a good choice forgood nutrition.